As a protocol to send and receive data files between a client terminal and a server, HTTP (Hyper Text Transfer Protocol) is used. When the client terminal acquires a data file from the server, for example, by notifying the server of a request (Hereinafter, it is called “data sending request”) by using GET method, the client terminal can desired data file. On the other hand, when the client terminal sends a data file to the server, for example, by notifying the server of a request (Hereinafter, it is called “data receiving request”) by using PUT method or POST method, the client terminal can send data as the data file having a desired destination. In the data sending request or the data receiving request, the desired data file is indicated by URL (Uniform Resource Locator) or a part of URL.
Furthermore, in HTTP protocol, in order to send and receive a part (partial data) of data file between the client terminal and the server, partial data sending/receiving request can be performed. For example, when the client terminal desires to acquire partial data of the data file from the server, the client terminal notifies the server of a partial data sending request. For example, in the request by using GET method, the client terminal notifies by indicating a desired data file with URL and by indicating a range of the partial data in the data file.
As an application example of the partial data sending request, in order to simultaneously acquire a plurality of different data in the data file, a method for simultaneously performing a plurality of partial data sending requests is known. By simultaneously sending a plurality of partial data sending requests to the server, the client terminal parallely acquires each partial data. By using this method, a time to acquire all data of the data file can be shortened.
However, in the conventional method, for example, when respective data is acquired from one data file by two partial data sending requests, a time required to acquire the respective data is often different between two partial data sending requests. For example, when a large data file such as video data is acquired, after partial data is acquired by one partial data sending request, it often takes a long time to wait completion of acquisition of partial data by the other partial data sending request. This problem similarly occurs in case of simultaneously sending a plurality of partial data in the data file.